obstinate or conceited with regard to the merit of one's own opinions; conceitedly dogmatic.
Origin of opinionated
Synonyms for opinionated
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for unopinionated
Historical Examples of unopinionated
Upon other matters connected with eating he was not so unopinionated.Mountain
holding obstinately and unreasonably to one's own opinions; dogmatic
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
"obstinate," c.1600, past participle adjective from opinionate.
Online Etymology Dictionary, © 2010 Douglas Harper